Recent advances in biological therapies for disc degeneration: tissue engineering of the annulus fibrosus, nucleus pulposus and whole intervertebral discs.

Advanced intervertebral disc (IVD) degeneration, a major cause of back pain in the United States, is treated using invasive surgical intervention which may cause further degeneration is the future. Because of the limitations of traditional solutions, tissue engineering therapies have become increasingly popular. IVDs have two distinct regions, the inner nucleus pulposus (NP) which is jelly-like and rich in glycosaminoglycans (GAGs) and the outer annulus fibrosus (AF) which is organized into highly collagenous lamellae. Tissue engineered scaffolds, as well as whole organ culture systems have been developed. These culture systems may help elucidate the initial causes of disc degeneration. To create an effective tissue engineered therapy, researchers have focused on designing materials that mimic the properties of these two regions to be used independently or in concert. The few in vivo studies show promise in retaining disc height and MRI T2 signal intensity, the gold standard in determining disc health.